Oxygen transport to muscle during exercise in chronic congestive heart failure secondary to idiopathic dilated cardiomyopathy

In chronic heart failure, oxygen delivery during exercise is impaired mainly because of failure of cardiac output to increase normally. Compensatory mechanisms are hemoglobin concentration increase, right-ward shift in the oxyhemoglobin dissociation curve, and blood flow redistribution from the nonexercising organs to the exercising muscles.     

The effect of low-intensity pulsed ultrasound on bone healing in SR-PLLA rod fixed experimental distal femur osteotomy in rat

The effects of low-intensity pulsed ultrasound (30 mW/cm²) were investigated in experimental cancellous bone fracture healing in bioabsorbable self-reinforced poly-l-lactide (SR-PLLA) rod fixed distal femur osteotomy in rats. A transverse transcondylar osteotomy was fixed with one SR-PLLA rod in 32 male Wistar rats of the age of 20 weeks. Half of the rats had a daily 20-min ultrasound exposure for three weeks. The follow-up times were three, six, and 12 weeks. Radiographical, histological, microradiographical, oxytetracycline labeling, and histomorphometrical analyses were performed. No foreign-body reactions were noted. The biocompatibility of SR-PLLA and ultrasound was found to be good. In the radiological and histological assessments there was a slight tendency for enhanced healing in the ultrasound group at three weeks, but at six and 12 weeks no differences were observed. The histomorphometrical and oxytetracycline labeling analyses showed that ultrasound exposure had no significant effects on bone healing. The present study shows that there were no obvious findings to support the hypothesis that low-intensity pulsed ultrasound enhances bone healing in self-reinforced poly-l-lactide (SR-PLLA) rod fixed experimental metaphyseal distal femur osteotomy in rats. The observed good biocompatibility provides a safe starting-point for clinical trials on bioabsorbable fixation combined with low-intensity ultrasound.     

The effect of process parameters on the hardness of surface densified Scots pine solid wood

This paper addresses the effect of surface densification on the Brinell hardness of Scots pine sapwood. Densification was performed in an open system under heat and compression using different compression temperatures and closing times. The hardness was measured using a modified Brinell hardness method. Furthermore, the density profiles of the samples were measured and their correlation to hardness analysed. It was found that the process parameters strongly affected the hardness of surface densified solid wood. This knowledge is relevant when optimising the densification process according to the properties required of the end-product. At 150 °C compression temperature and 0.5 min closing time, the average Brinell hardness (23.4 N/mm²) was double to that at 200 °C and 5 min closing time (11.6 N/mm²).     

Reducing the set-recovery of surface densified solid Scots pine wood by hydrothermal post-treatment

The mechanical properties of wood surface are of particular interest in applications where mainly the surface is exposed to use, such as flooring boards. Wood surface densification aims to improve these properties by compressing only the first few millimeters beneath the surface. Scots pine (Pinus sylvestris L.) sapwood was surface densified to three degrees of compression at 150 °C using a specially designed heated press. Half of the specimens were hydrothermally post-treated at 200 °C. To study the influence of the degree of compression and hydrothermal post-treatment on the set-recovery, specimens were subjected to water soaking-drying-cycles. The surface densification process resulted in a minor mass loss regardless of the degree of compression, whilst the hydrothermal post-treatment led to an average mass loss of 3.8 % in surface densified specimens and of 4.1 % in control un-densified specimens. Furthermore, considerable fixation of compressive deformation was obtained by hydrothermal post-treatment at 200 °C.     

Perceived racial/ethnic discrimination, posttraumatic stress symptoms, and health risk behaviors among Mexican American adolescents.

Utilizing the concept of race-based traumatic stress, this study tested whether posttraumatic stress symptoms explain the process by which perceived discrimination is related to health risk behaviors among Mexican American adolescents. One hundred ten participants were recruited from a large health maintenance organization in Northern California. Mediational analyses indicated that adolescents who perceived more discrimination reported worse posttraumatic stress symptoms, controlling for covariates. In turn, adolescents who experienced heightened posttraumatic stress symptoms reported more alcohol use, more other drug use, involvement in more fights, and more sexual partners. Perceived discrimination was also directly related to involvement in more fights. Results provide support for the notion of race-based traumatic stress, specifically, that perceived discrimination may be traumatizing for Mexican American adolescents. Counseling psychologists and counselors in schools and community settings should assess Mexican American adolescents for the effects of discrimination and provide appropriate interventions to reduce its negative emotional impact. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social support, problem solving, and the longitudinal course of newlywed marriage.

Married couples (N = 172) were observed as newlyweds and observed again 1 year later while engaging in 2 problem-solving and 2 personal support discussions. Microanalytic coding of these conversations was used to examine associations between problem-solving and social support behaviors for 1 year and their relative contributions to 10-year trajectories of self-reported relationship satisfaction and dissolution. Results demonstrated that initially lower levels of positive support behaviors and higher levels of negative support behaviors predicted 1-year increases in negative emotion displayed during problem-solving conversations. Emotions coded from the initial problem-solving conversations did not predict 1-year changes in social support behaviors. Controlling for emotions displayed during problem-solving interactions eliminated or reduced associations between initial social support behaviors and (a) later levels of satisfaction and (b) relationship dissolution. These findings corroborate models that prioritize empathy, validation, and caring as key elements in the development of intimacy (e.g., Reis & Shaver, 1988) and suggest that deficits in these domains foreshadow deterioration in problem solving and conflict management. Implications for integrating support and problem solving in models of relationship change are outlined, as are implications for incorporating social support in education programs for developing relationships. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Change in hormones reflecting sympathetic activity in the Finnish sauna

The effects of the high temperature (80-120 degrees C) of the Finnish Sauna bath on the concentrations of growth hormone, immunoreactive insulin and renin activity in plasma, on blood glucose and on the urinary excretion of aldosterone, vanilmandelic acid and sodium of 55 healthy volunteers were studied. There was a significant increase in mean heart rate (62%), serum growth hormone (142%) and plasma renin activity (95%) in the Sauna. One hour after the Sauna bath the mean serum growth hormone had returned to the control level while plasma renin activity still remained higher (p less than 0.05) than before the Sauna bath. The serum insulin, blood sugar and urinary excretion of aldosterone and VMA did not change during or after Sauna bath. The urinary sodium excretion decreased significantly after the Sauna bath and the decrease was most striking (46%) during the first 6-hour period from the beginning of Sauna bath. Plasma renin activity values correlated positively with 12-hour urinary VMA excretion (p less than 0.01) and negatively with 6-hour urinary sodium excretion (p less than 0.05) before and after Sauna, suggesting the role of catecholamines and sodium depletion in renin response in Sauna.